Apparatus for controlling the operation of directional switches in signalling systems



Feb. 11, 1958 2,823,265

MERTEL APPARATUS FOR CONTROLLING THE OPERATION OF DIRECTIONA SWITCHES IN SIGNALLING SYSTEMS Filed Jan. 28, 1955 3 SheetsSheet 1 Filed. Jan. 28, 1955 Feb. 11, 1958 H. MERTEL 2,823,265

APPARATUS "FOR CONTROLLING THE OPERATION OF DIRECTIONAL SWITCHES IN SIGNALLING SYSTEMS 3 Sheets-Sheet 2 Feb. 11, 195 H. MERTEL 2,823,265

APPARATUS FOR CONTROLLING THE OPERATION OF DIRECTIONAL SWITCHES IN SIGNALLING SYSTEMS Filed Jan. 28, 1955 3 Sheets-Sheet 3 6 Ml: 63Z321 F WRlI flue'z for United States Patent APPARATUS FOR CONTROLLING THE OPERA- TION OF DIRECTIONAL SWITCHES IN SIG- NALLING SYSTEMS Heinz Mertel, Munich, Germany, assignor to Siemens &

Halske Aktiengesellschaft, Munich and Berlin, Germany, a German corporation Application January 28, 1955, Serial No. 484,719 Claims priority, application Germany February 23, 1954 Claims. (Cl. 179-18) This inventionv is concerned with a circuit arrangement for controlling the operation of directional switches, for example, of group selector switches, in signalling systems', especially telephone systems;

The setting of the wipers directional switches with respect to different trafiic directions, rather to say, with respect to bank contacts of line or trunk groups to which are connected lines or trunks extending in the cone spending trafiic directions may be accomplished in different ways. In accordance with one mode of operation; the trunk groups may be marked by means of marker switches having wipers which may be set in accordance with dial impulse series characterizing the different traffic directions. A directional switch operating in two directions of motion (vertical-rotary wiper motion) is operated to. set its wipersin, position corresponding to the start of a. marked decade or level or, assuming'a switch having only one direction of motion, for example a rotary switch, is operated to set its wipers in position corresponding to the start of a group of marked bank contacts of a desired trunk group. Each type of switch is thereafter operated to hunt for bank contacts associated with an. idle trunk in the corresponding group. In case a marker switch is provided for cooperation with a plurality of directional switches, the arrangement would be such that only one of these directional switches can at any time coact. with the marker switch; the other directional switches would be in the meantime blocked producing a corresponding blocking of traflic. The usual practice therefore is. to provide a marker switch for each directional switch. The. marking of the desired traffic direction by thev marker switch must in such a case be effected in the circuit of the directional switch. This means the bank multiple mustv be cut. at the first bank contact of each trunk. group or at an intermediate resting position preceding the start of a trunk group, so as to prevent the setting of, the wipers of other switches in engagement with bank contacts extending in wrong directions. The consequence of this is however that alterations. as to the number of trunks in the various groups becomes difi'icult because it would require soldering. operations, at the cut multiple and corresponding cutting at other desired points, thus requiring considerable work and increasing the danger of producing faulty soldering points.

The invention avoids these drawbacks by the provision.

of a marker device comprising switching means for marking the beginning and the end of trunk groups extending in the various call directions, and making in these positions switching control means effective for initiating the hunting operations of the directional switch in the desired call direction, said control means being. responsive to finding all trunks in such. direction busy further effective to cause the directional switch, to continue its stepping operation relative to the bank contacts associated with other trunk' groups until the start position'of the originally marked group is reached again. In

accordance with another feature of the invention, the

test circuit of the directional switch is interrupted during the stepping of the wipers relative to the bank contacts belonging to undesired groups.

The arrangement according to the invention requires in the event of alterations in the number of trunks in the various groups merely establishment of a connection ofvthe new start and end positions of a group with correspondingmarker positions in the marker device, or, if a marker switch is used, with the corresponding bank contacts thereof. The disconnect contacts for the interruption of the test circuit responsive to busy condition of all trunks in a group. are disposed at the ends of the respective groups, and these contacts are simply correspondingly shifted in the multiple of the contact bank provided therefor.

The invention will now be described with reference to the accompanying schematic drawings wherein Figs. 1a and 1b, when placed side by side with corresponding conductors in alignment, show an example of the invention;

Fig. 2 shows the use of the invention for several trunk r p Fig. 3 shows a circuit portion based on Fig. 1 in which the sequence of successive line or trunk groupsmay be exchanged; and

Fig. 4 indicates an arrangement for successively testing (hunting for) trunks in several trunk groups responsive to marking of one trunk group for the hunting operation.

Referring now to Figs. 1a-1b, RW indicates as an example of a. directionalswitch a; group selector serving at the same time as a directional switch which is preferably made in the form of a large capacity motordriven one hundred point switch. The wipers a, b, a1, b1 serve for extending four-conductor trunks. Auxiliary or control wipers c, d, e, f are additionally provided, the function of which willbe presently explained. The drive motor comprises known field magnets M1, M2 which are displaced one relative to the other by These field magnets are. alternately switched in by cam contacts m1 and m2 which are controlled from the motor shaft. Atthe time when the field magnet M1 is energized, the cam contact m2 is closed and m1 is open; conversely, when the field magnet M2 is energized, cam contact m1 will be closed and m2 will be open. Simultaneously energization of both field magnets causes stopping of the switch. The alternate energization of the two magnets M1 andM2 causes rotation of an armature rotatably disposed therebetween and such. armature drives a gear to rotate the wiper carrier provided on the switch shaft. A switch of this kind is described in copending application Serial No. 269,224, filed January 31, 1952, now Patent No...2,701,824; examples of drive motors are described insPatents Nos. 2,002,546 and 2,654,846. An example of a control circuit for such a motor-driven rotary switch may be had from Patent No. 2,691,699.

The group selector switch RW usually has in accordance with the decade system access to ten trunk groups each having ten. trunks. It is; understood, of course, that a group may as desired or required have more or fewer trunks and more or fewer than ten groups may likewise be provided. The number of steps or effective positions of a marker switch is governed, by the number of trunk groups. In Fig. lb, there are shown for simplicity only four trunk groups N1 to N4, extending in different call or trafiic directions. Preceding the first bank contacts, (start) of each, trunk group there is provided a. resting position as indicated at r1, r2, r3, 114. These resting, positions also mark. the end positions of the, respectively preceding trunk groups. These reste nd positions may also be referred to. as transit positions which are reached by the corresponding switch wipers responsive to busy condition of all trunks in the respectively preceding groups.

Associated with the selector switch RW is a rotary switch having a few positions, for example, a so-called selector relay WR having switch arms or wipers WRI and WRII. The wiper WRI determines in the contact bank to which it has access the start of the marked trunk group over a wiper f of the group selector switch in the rest position r1 of the latter prior to the start of a group. The wiper WRII of the marker switch determines in the contact bank to which it has access the end positions (transit positions) of the marked groups over connections of its bank contacts which are by one step displaced relative to the rest positions reached over the wiper f of the group selector'switch.

The group selector switch RW is provided with otfnormal contacts n1, n2, n3 (Fig. 1a) which are actuated when the switch rotates out of its normal position. The marker switch WR is provided with similar otf-normal contacts wroI, wroII, and with a contact wrII which is controlled by the selection magnet.

The operation of the circuit is as follows:

7 Upon seizure of the group selector switch RW by a preceding switch (not shown), the seizure relay C (Fig. la) will energize in a circuit extending over the incoming private conductor a and closed contacts n3 and d3. Upon energizing, the relay C closes its contact 01, thereby completing a holding circuit for itself independent of contacts n3 and d3. At contacts c3 (Fig. 1b), relay C prepares a testing and recording circuit; at contact c2 (Fig. 1b), a circuit is prepared for relay U which is controlled by contacts gl-g4 respectively governed by disconnect relays such as G1. The disconnect relays such as G1 restore when all trunks in an associated trunk group are found busy. Contact c4 (Fig. 1a) of relay C is opened to prepare for the operation of the field magnets M1, M2 of the selector switch RW.

The dial impulse series which determines the desired call direction or rather to say the group of trunks extending in the desired direction arrive over the incoming conductor d (Fig. 1a) and are received by the impulse relay A connected to such conductor over a contact 12 controlled by test relay P. Relay A is accordingly energized in impulse manner by the transmitted dial impulse series.

It shall first be assumed that the first impulse series consists of a single impulse. Relay A upon actuating closes its contact a1, thereby closing a circuit for the energization of the magnet WR of the marker relay switch. The wipers WRI and WRII of the marker switch accordingly execute one step, thus leaving normal position. The off-normal contact wroII (Fig. 1a) is closed, thereby completing a circuit for the energization of the motorswitch-in relay D which extends from p3, a3, wroII and both windings DII and DI to Relay B (Fig. 1b) which has a contact b1 (Fig. 1a) disposed in the motor stop circuit is energized at the time when relay D energizes, the corresponding circuit extending from u3, wiper WRI (position 1), f (position r1), B to Upon operating, relay B closes its contact b1 thereby completing an energizing circuit for both field magnets M1 and M2 from ground at contact d1 which closes upon energization of relay D. Both field magnets M1 and M2 are energized and the group selector switch RW is accordingly prevented from starting to rotate its wipers, being held in its normal position.

Upon deenergization of the impulse relay A responsive to receipt of the first impulse series (one impulse), relay D will deenergize also, its circuit being interrupted at contact a3. It deenergizes with some delay due to the action of its winding DII which had been shunted by contact d2. Upon deenergization of relay D, a test is made over the wiper e of the selector switch to establish the trunk seizure g1, rest position r1, wiper e, p4, winding I of relay U, d4, (:2, wrII, wroI to Upon energizing, relay U opens its contact :13, thereby interrupting the circuit for relay B which deenergizes, opening its contact b1 and thereby freeing the directional switch for starting its rotation. Relay U after deenergization of relay B, continues to hold over its own contact a1 and its winding 11 (Fig. 1a) in a circuit from p3, b3, 1, a7, UH to Winding UIII is shunted by contact u7 to prepare for subsequent delayed release of relay U. By closing its contact 146 (Fig. 1b), relay U prepares the testing circuit. Upon deenergization of relay B, relay D is again energized in a circuit from p3, uS, wroII, DH, DI to The field magnet M1 which until now was energized together with field magnet M2 due to closure of contact b1, preventing rotation of the drive motor of the selector switch can now, after deenergization of relay B become efiective in the circuit extending from d1, m1, M1 to The field magnets M1 and M2 of the selector switch RW are now alternately energized by the operation of the cam contacts m1 and m2, and the wipers a to e (Fig. lb) are accordingly in hunting fashion rotated for the purpose of finding bank contacts of an idle trunk in the marked trunk group N1. When an idle trunk is reached, the test relay P (Fig. 1b) will energize in a circuit from 03, d5, a6, windings I and II of P, wiper c to Upon energizing, relay P closes its contact p1, thereby causing energization of both field magnets M1 and M2 and consequently stopping the rotation of the selector switch with its wipers in engagement with bank contacts connected with the trunk found idle. The high-resistance winding I of the test relay P is shunted by its own contact p2, thereby busying the seized trunk against seizure by other switches. At contact p3, relay P disconnects the relay D.

If the selector switch RW does not find an idle line in the marked group, during its hunting rotation, it will continue to rotate to the transit position r2 which also constitutes the start position for the next successive trunk group N2. In position r2, a circuit is again closed for the stop relay B of the selector switch which extends from a2, WRII (position 1), r2, wiper f, winding of B to Relay B closes its contact b1, again connecting both (:3, d5, a6, b2, wiper d, ZR to The holding circuit for the switch-over relay U is' opened at contact b3. Relay U deenergizes with some delay due to the shunt across its winding III. The deenergization of relay U causes opening of the contact 142' and consequent deenergization of the relay B which opens its contact b1 and thereby causes the switch to rotate'again. The relay U having been deenergized, has

opened its contact 146 (Fig. lb), to prevent testing during the rotation of the wipers over the bank contacts of all trunks of all groups following the originally marked group N1 until the start position r1 of the marked group is reached again.

When such start position is reached, relay B will energize again over the wipers WRI and) and will stop further rotation by closing its contact b1. Upon energizing, relay B opens its contact b3 causing relay D to deenergize.

If no trunk of the desired group N1 has become idle up to this instant, the switch-over relay U will not energize because the disconnect contact g1 connected with the rest position r1 is still open. Relay B remains energized for the time being and the switch waits with its wipers on the rest position until a trunk becomes idle.

When this happens, the disconnect contact g1 will be closed due to energization. of relay G1. The switchover relay U is accordingly energized causing deenergization of relay B, therefore energization of relay D and terminating the stopping of the selector switch which begins to rotate its wipers again to hunt for the idle trunk in the desired trunk group.

Upon finding the idle trunk, the test relay P will energize and the directional switch is accordingly stopped, as described before, with its wipers in engagement with the seized idle trunk.

In the event that all trunks of the corresponding group have meantime become busy again, the selector switch will again rotate to the transit position or rather to say to the rest position 12 at the start of the next group in which position the relay B is again energized over the wipers WRII and f causing stopping of the switch. After an interval, the selector switch rotates its wipers again over the bank contacts of the successive trunk groups to the originally marked rest position.

If the incoming impulse series designates a group other than group N1, for example, by three impulses the group N3, the first impulse will cause stepping of the marker switch WR by one step, as described before, while the selector switch is held in stop position. Upon receipt of the second and. the third impulse, the marker switch WR is again stepped in each instance by one step, until its wipers WRI and WRII are in position 3. Relay B now deenergizes and the selector switch RW is consequently free to rotate, lagging behind the marker switch until its wiper reaches the position marked by the marker switch which is in the assumed case position 3. This position. corresponds to the rest position r3 which precedes the trunk group N3. Relay B is now again energizedover a circuit including the wipers WRI and f and, stops further rotation of the selector switch by closing its contact [11, thereby causing both field magnets M1 and M2 to energize. The further switching operations following the positioning of the switch wipers at the start of the marked group N3 correspond to those described before in connection with the hunting in the trunk group N1.

The release of the selector switch and of the marker switch depends on the release of the preceding switch at which the conductor c is interrupted. The seizure relay C accordingly deenergizes causing opening of, the contacts 03 and c2 and consequent release of relays P and U. Upon release of these relays, the relay D will energize over the off-normal contact 112 in a circuit extending from p3, b3, n4, n2, windings I and II of D to The selector switch starts rotating again, stepping into the normal position in whichit isstopped by simultaneous energization of the field magnets. M1 and M2 in a circuit extending over contacts 04, n1. (M2) and 04,111, b1 (M1). Oif-normal contact n2 is opened in the normal position of the selector switch and relay" D accordingly deenergizes with some delay due to the shunt around its. winding 11.

Upon release of relay C, relay A is energized over its winding II (Fig. lb) in a circuit from A11, 05, wrII, wroI to At contact a1, relay A switches. in the marker switch magnet WR. This operation. causes opening of contact wroI and consequent interruption of the circuit of relay A winding 11. Relay A deenergizes interrupting the circuit for the marker switch magnet WR and the latter, upon deenergizing, closes its contact wroI thereby again closing the circuit for relay A over its winding 11, reenergizing relay A. This interplay between the relay A and the magnet WR causes stepping of the marker switch to its normal or home position in which the contact wroI is opened to disconnect relay A.

In the embodiment according to Figs. la and lb, the arrangement is such that the marker switch which is positioned by the dial impulse series always marks only one trunk group and always that group which corresponds to the digit impulses transmitted. In other words, the groups are numerically successively placed in the bank multiple of the selector switch. The transit position of one group constitutes always the start position of the numerically next successive trunk group.

If it is desired to test not only the trunks of a group that has been marked but immediately thereafter the trunks of the next successive group or of several successive groups, it will be necessary in accordance with the arrangement of Fig. 4 to mark with the wiper WRII of the marker switch the end positions of the trunk groups to be tested in the hunting operation instead of marking with such wiper the rest position which is displaced relative to rest position marked by wiper WRI. For example, if it is desired that the trunks in the groups N2 and N3 should be subjected to testing responsive to the marking of group N2 or, in other words, that the selector switch should step over from the group N2 to the group N3, if the trunks in Nlare found busy, the positions 2 and 3 of the wiper WRII are connected together as shown in Fig. 4 and interconnected with the end position r4 of the group N3 at the selector switch.

It is understood, of course, that more than two trunk groups may in such manner be tested in the hunting opera.- tion. The corresponding positions are in such a case connected in the contact bank accessible to wiper WRII and analogously interconnected with the end rest positions of the last trunk group to be tested.

According to the arrangement of Fig. 2, the trunk group that is to be tested in the overrunning hunting operation must not directly follow the marked group; several trunk groups which are not to be tested may be disposed between the marked group and the group to be thereafter tested. Fig. 2 also shows the use of the invention for simultaneously testing in several trunk groups. The marker switch is also adapted to be set so as to reach. by-pass traflic directions in the event that the trunks in a direct direction are busy. It is in this manner possible to coincidentally mark and hunt along a detour. Fig. 2 which merely illustrates an example of the wiring between the contact bank accessible to the wiper f of the selector switch and the contact bank accessible to the wiper WRI of the marker switch of Figs. la--lb, showing as an example, that it is possible to mark in the marker position 2 not only the trunk group N2 but also the trunk group N6 in the selector switch. Accordingly, if the trunks in the. group N2 are found busy, the switch will not run over all bank contacts of the succeeding trunk group to the marked start position r2 of the group N2, but will be stopped in the rest position r6 of the trunk group N6 which has likewise been marked in accordance with the position 2 and will test for an idle trunk exactly as it tested in group N2. The trunk group N6 accordingly serves in the manner of a detour for the trunk group N2 in case all trunks in the latter are found busv.

Inthe event that all trunks in the coincidentally 7 marked trunk group N6 are found busy, the selector switch will rotate its wipers over the bank contacts of all succeeding trunk groups without any testing until it reaches position r2 of the originally marked trunk group N2 which is interconnected with position 16 of trunk group N6. The trunk group N2 does in such a case not serve as a detour for the trunk group N6 because of the decoupling element, preferably a rectifier GRl provided in the wiring which interconnects the two rest positions r2 and r6, which in such position blocks the circuit for the stop relay B.

Fig. 2 also indicates that the trunk group N7 may serve as a detour for the trunk groups N3 and N4; the latter groups N3 and N4 cannot serve in such arrangement as detours for N7 because of the decoupling elements GR2 and GR3 provided in the corresponding wiring.

Fig. 3 is a fractional circuit based on Fig. 1, showing an embodiment in which the sequence of the successive trunk groups may be exchanged in the multiple of the selector switch while the marker switch is still set in accordance with the numerical succession. In this embodiment, the selector switch must be temporarily stopped ahead of the exchanged trunk group until it is determined which of the group is to be tested or whether the normal group succession is in order.

In accordance with Fig. 3, the groups 4 and 5 and the groups 0 and 8-9 are exchanged to give an example If it is assumed that the trunks in group 5 are busy, the directional switch will rotate to the start position r4 of the group N4 as an overrunning position. As shown in the figure, a stop circuit is completed for the selector switch as soon as the wiper WRI of the marker switch reaches position 4. During the receipt by the marker switch of the impulse series designating the desired traffie direction, a slow-to-release control relay V (Fig. 1b) is energized over contact a6 which causes energization of the relay B over its contact v3 (Fig. 3) and relay B in turn stops the selector switch ahead of the group N5 in a manner described before. Relay D (Fig. 1a) is at the same time prevented from operating by the closure of contact v2 until such time when relay V releases. Only then can the selector switch rotate its wipers again, rotating them .to the start position of the desired trunk group marked by the marker switch, for example, to the position 4, provided the marker switch has received four impulses, or if the marker switch has received five impulses, the wipers remain stopped in position 5. In case the marker switch has, for example, received six impulses, the selector switch will rotate its wipers out of position 5 at the moment when the marker switch rotates its wipers over position 4 into position 6.

The arrangement according to Figs. 2 and 3 is not only useful for selector switches which repeat the hunting operation depending upon a busy trunk-disconnect operation, but also for selector switches which execute the hunting without disconnect control only once and run in case of busy condition to a run-over position in which a busy signal is connected. One purpose of the arrangement is to make it possible to provide for a running over from numerically higher to numerically lower trunk groups.

Changes may be made within the scope and spirit of the appended claims.

-I claim: 1. In a telephone system having a directional switch for building up calls over trunk lines which are arranged in groups extending respectively in different traffic directions, said trunk lines of said groups being accessible to said switch over bank contacts respectively connected therewith and arranged in corresponding groups and overwipers which are operable by said switch in a hunting operation relative to such groups of bank contacts, apparatus for controlling the hunting operation of said directionalfswitch, said apparatus comprisinga marker switch'eoopera'ting with said directional switcl1,'cir cuit means for transmitting to said marker switch impulse series indicating a desired trafiic direction over which a call is-to'be extended thereby, means in said marker switch responsive to the receipt'of said impulse series for marking the start and the end positions of bank contacts allotted to the group of trunk lines extending in the traffic direction indicated by said impulse series, circuit means for causing said directional switch to move its wipers for hunting for an idle line in the marked group of trunk lines, and circuit means effective if all trunk lines are busy in such group for causing said directional switch to move its wipers over the bank contacts connected with trunk lines of all other groups extending in other trafiic directions to position said wipers again in start position of the bank contacts of the group marked 'by. said marker switch for the purpose of repeating the hunting operation for an idle trunk line in such marked group.

2. A system and cooperation of parts as set forth in claim 1, comprising a test circuit in said directional switch for testing for an idle line during the hunting operationthereof, and means for interrupting said testing circuit during the motion of said wipers relative to bank contacts allotted to said other groups which extend in other tralfic directions.

3. A system and cooperation of parts as set forth in claim 1, comprising wiper means in said marker switch for scanning the positioning of the wipers of said directional switch.

4. A system and cooperation of parts as set forth in claim 3, wherein said wiper means comprises a pair of Wipers for respectively marking the start and end positions of the bank contacts associated with the group of trunk lines extending in the desired traffic direction, said end position corresponding to the start position of the next successive group of trunk lines.

5. A system and cooperation of parts as set forth in claim 4, comprising a control contact bank in said directional switch, a wiper operated by said directional switch relative to said control contact bank for marking the respective start and end positions of said trunk groups in such control contact bank, a contact bank associated with each of said pair of wipers, said start and end positions in said control contact bank being successively connected with the successive contacts in said contact banks accessible to said pair of wipers, the contacts in one of said last named contact banks being by one position displaced relative to the contacts in the other one of said contact banks.

6. A system and cooperation of parts as set forth in claim 3, comprising circuit means for causing the setting operation of said directional switch to lag behind that of said marker switch.

7. A system and cooperation of parts as set forth in claim 1, comprising means for holding said directional switch with its wipers on said start position until such a time when a line becomes idle in said marked group.

8. A system and cooperation of parts as set forth in claim 1, comprising means for causing said directional switch to move its wipers repeatedly over the bank contacts of the marked group of trunk lines and thereafter over said other bank contacts back to the start position of the desired group.

9. A system and cooperation of parts as set forth in claim 1, comprising means for temporarily stopping said directional switch with its wipers in the end positions of the bank contacts associated with the marked group of trunk lines, if all trunks in such group are found busy, a recording device, and circuit means for transmitting a recording pulse to saiddevice duringthe temporary stopping of said directionalswitch.

10. A system and cooperation of parts as set forth in claim 1, comprising circuit means for marking in one marking position of said marker switch a plurality of groups-of trunk lines over which the corresponding call maybe extended; .1

11. A system and cooperation of parts as set forth in claim 10, comprising circuit means for connecting together the end positions of certain of said marked groups in said marker switch and interconnecting such connected positions with the end position of another group.

12. A system and cooperation of parts as set forth in claim 10, comprising a first bank of control contacts associated with said directional switch, contacts in said control bank designating said start and end positions of said groups of trunk lines, a second bank of control contacts associated with said marker switch, circuit means for interconnecting certain contacts in said first control bank with predetermined contacts in said second control bank, and circuit control means in said circuit means for marking designated positions of certain groups of trunk lines as detour trunk lines for routing calls.

13. A system and cooperation of parts as set forth in claim 10, comprising circuit means controlled by said marker switch for numerically successively marking said groups of trunk lines, and circuit means in the multiple of said directional switch for exchanging the numerical succession of said groups of trunk lines.

14. A system and cooperation of parts as set forth in claim 13, comprising switching control means for causing said directional switch to lag behind said marker switch until its wipers reach the start position of an exchanged group of trunk lines, means for thereupon stopping said lirectional switch, and means controlled by said marker for thereupon marking the desired group of trunk lines.

15. A system and cooperation of parts as set forth in claim 14, comprising a relay which is energized during the receipt of an impulse series by said marker switch, and contact means controlled by said relay for governing the stopping of said directional switch.

References Cited intthe file of this patent UNITED STATES PATENTS 2,660,619 Kessler Nov. 29, 1953 

